Neandertal Gene Study Reveals Early Split With Humans

Noonan's work represents a significant advance over earlier studies of Neandertal genetics, such as those conducted by William Goodwin of the University of Glasgow in Scotland. (Related: "Neandertals Not Our Ancestors, DNA Study Suggests" [May 14, 2003].)

That early work involved analysis of mitochondrial DNA, which tends to stay preserved longer than DNA found inside the nuclei of cells. But Noonan analyzed nuclear DNA, which holds a much greater wealth of information.

"Nuclear DNA is where all the biology is," Noonan said. "We want to understand how traits like language and cognition are encoded, and none of those traits can be found in mitochondrial DNA."

Race to the Finish

Like the multiple groups who worked simultaneously to sequence the human genome, Noonan faces competition from other inspired teams.

Genetic anthropologist Svante Paabo of the Max Planck Institute in Leipzig, Germany, is working on a similar sequencing project using DNA from bone specimens belonging to a Neandertal who lived in Croatia about 45,000 years ago.

"A Neandertal genome sequence will provide a catalog of all changes that happened in the human genome after humans separated from Neandertals, so it will be a wonderful tool for scientists who want to find out what makes modern humans unique," Paabo said.

While Noonan's focus is on studying the sequences of Neandertal DNA he considers most significant—those he can compare to modern human DNA sequences—Paabo's goal is to sequence the entire Neandertal genome within two years.

Based on his results to date, Paabo expects to see some surprises as his project proceeds.

"Neandertal DNA is degraded in specific ways that we had not anticipated, and in some ways Neandertals actually look closer to humans than we had expected," he said.

The Natural History Museum's Potts hopes Noonan's and Paabo's investigations, in addition to fleshing out Neandertals' genetic profile, will lend insight into their day-to-day existence, including the challenges they faced that shaped specific genetic adaptations.

"The genetic analysis of Neandertals complements the study of fossils and the archaeological record of Neandertal behavior," he said.

"All this evidence allows us to understand exactly how Neandertals lived and adapted to a changing world that eventually included our species."